Well according to the notes vampric touch did receive an incredibally small nerf (87% - 79%) 79% * 1.1 = 86.9%

So a .1% nerf which was more then outbalanced by most of the other abilities being above their pre 7.1 values with shadowform. Its either an overnerf that wasn't documented (which there are quite a few of) or a tooltip error. We will see after logs from tonight come out.

Incrementally small, should be aligned when using shadowform into voidform within rotation.

The issue people are seeing with Vampiric Touch is most likely a tooltip issue caused by the tooltip not reading Haste, but I will bring it up.